1. Field of the Invention
This invention generally relates to a catheter and more particularly, to a catheter for use in treating blood vessels or other body organs with medicaments.
2. Prior Art
For the treatment of various diseases, it is often desired to administer a high concentration of medicament to lesions in human body organs or vessels. In an attempt to provide an effective amount of medicament to the lesion through general oral administration and phleboclysis, some medicaments would produce side effects of giving so serious damage to other sites as to bring the patient in danger or causing chill and pain to the patient. Despite their superior pharmaceutical effect, these medicaments cannot be applied to the lesion in practice.
For the treatment of intrinsic intravascular stenosis, typically coronary stenosis, angioplasty using dilating balloon catheters has been widespread over decades. See Gruntig, The New England Journal of Medicine, Vol. 301, No. 2, 12/6/1979, pages 61-68. The angioplasty is a therapy of percuteneohsly inserting a balloon catheter into the coronaria until the balloon reaches a stenosis, and inflating the balloon to dilate the stenosis. It is less invasive and hence, imposes a less physical burden to the patient as compared with surgical operation. One outstanding problem of the angioplasty is relatively high recurrence of once dilated intravascular stricture. To prevent recurrence, attempts are made to administer to the focus or dilated vessel inner wall various anti-restenosis agents, anti-thrombotic agents, thrombolytic agents, decalcifying agents, anti-calcifying agents, certain cytokines, cytostatic agents, and vectors for controlling the propagation of smooth muscle cells.
Japanese Patent Application Kokai (JP-A) No. 283380/1990 discloses a balloon which is perforated with pores for injecting medicament. This balloon fails to administer an appropriate effective amount of medicament to the lesion under desirable conditions since the size of medicament injecting pores cannot be controlled. For example, the balloon fails to accommodate a variety of strictures of different lesion where it is desired to administer medicament fluid with the balloon inflated under a low pressure or where medicament administration under a high pressure is not desired.